src/modules/robot/Planner.cpp

   1 /*
   2       This file is part of Smoothie (http://smoothieware.org/). The motion control part is heavily based on Grbl (https://github.com/simen/grbl) with additions from Sungeun K. Jeon (https://github.com/chamnit/grbl)
   3       Smoothie is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
   4       Smoothie is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
   5       You should have received a copy of the GNU General Public License along with Smoothie. If not, see <http://www.gnu.org/licenses/>.
   6 */
   7
   8 using namespace std;
   9 #include <vector>
  10 #include "mbed.h"
  11 #include "libs/nuts_bolts.h"
  12 #include "libs/RingBuffer.h"
  13 #include "../communication/utils/Gcode.h"
  14 #include "libs/Module.h"
  15 #include "libs/Kernel.h"
  16 #include "Block.h"
  17 #include "Planner.h"
  18 #include "Player.h"
  19
  20
  21 Planner::Planner(){
  22     clear_vector(this->position);
  23     clear_vector_double(this->previous_unit_vec);
  24     this->previous_nominal_speed = 0.0;
  25     this->has_deleted_block = false;
  26 }
  27
  28 void Planner::on_module_loaded(){
  29     this->on_config_reload(this);
  30 }
  31
  32 void Planner::on_config_reload(void* argument){
  33     this->acceleration =       this->kernel->config->value(acceleration_checksum       )->by_default(100 )->as_number();
  34     this->max_jerk =           this->kernel->config->value(max_jerk_checksum           )->by_default(100 )->as_number();
  35     this->junction_deviation = this->kernel->config->value(junction_deviation_checksum )->by_default(0.05)->as_number();
  36 }
  37
  38
  39 // Append a block to the queue, compute it's speed factors
  40 void Planner::append_block( int target[], double feed_rate, double distance, double deltas[] ){
  41
  42     // Do not append block with no movement
  43     //if( target[ALPHA_STEPPER] == this->position[ALPHA_STEPPER] && target[BETA_STEPPER] == this->position[BETA_STEPPER] && target[GAMMA_STEPPER] == this->position[GAMMA_STEPPER] ){ this->computing = false; return; }
  44
  45
  46
  47     // Stall here if the queue is ful
  48     //this->kernel->serial->printf("aaa\r\n");
  49     while( this->kernel->player->queue.size() >= this->kernel->player->queue.capacity()-2 ){
  50         wait_us(500);
  51     }
  52     //this->kernel->serial->printf("bbb\r\n");
  53
  54     Block* block = this->kernel->player->new_block();
  55     block->planner = this;
  56
  57     // Direction bits
  58     block->direction_bits = 0;
  59     char direction_bits[3] = {this->kernel->stepper->alpha_dir_pin, this->kernel->stepper->beta_dir_pin, this->kernel->stepper->gamma_dir_pin};
  60     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){
  61         if( target[stepper] < position[stepper] ){ block->direction_bits |= (1<<direction_bits[stepper]); }
  62     }
  63
  64     // Number of steps for each stepper
  65     for( int stepper=ALPHA_STEPPER; stepper<=GAMMA_STEPPER; stepper++){ block->steps[stepper] = labs(target[stepper] - this->position[stepper]); }
  66
  67     // Max number of steps, for all axes
  68     block->steps_event_count = max( block->steps[ALPHA_STEPPER], max( block->steps[BETA_STEPPER], block->steps[GAMMA_STEPPER] ) );
  69     //if( block->steps_event_count == 0 ){ this->computing = false; return; }
  70
  71     block->millimeters = distance;
  72     double inverse_millimeters = 0;
  73     if( distance > 0 ){ inverse_millimeters = 1.0/distance; }
  74
  75     // Calculate speed in mm/minute for each axis. No divide by zero due to previous checks.
  76     // NOTE: Minimum stepper speed is limited by MINIMUM_STEPS_PER_MINUTE in stepper.c
  77     double inverse_minute = feed_rate * inverse_millimeters;
  78     if( distance > 0 ){
  79         block->nominal_speed = block->millimeters * inverse_minute;           // (mm/min) Always > 0
  80         block->nominal_rate = ceil(block->steps_event_count * inverse_minute); // (step/min) Always > 0
  81     }else{
  82         block->nominal_speed = 0;
  83         block->nominal_rate = 0;
  84     }
  85
  86     //this->kernel->serial->printf("nom_speed: %f nom_rate: %u step_event_count: %u block->steps_z: %u \r\n", block->nominal_speed, block->nominal_rate, block->steps_event_count, block->steps[2]  );
  87
  88     // Compute the acceleration rate for the trapezoid generator. Depending on the slope of the line
  89     // average travel per step event changes. For a line along one axis the travel per step event
  90     // is equal to the travel/step in the particular axis. For a 45 degree line the steppers of both
  91     // axes might step for every step event. Travel per step event is then sqrt(travel_x^2+travel_y^2).
  92     // To generate trapezoids with contant acceleration between blocks the rate_delta must be computed
  93     // specifically for each line to compensate for this phenomenon:
  94     // Convert universal acceleration for direction-dependent stepper rate change parameter
  95     block->rate_delta = ceil( block->steps_event_count*inverse_millimeters * this->acceleration*60.0 / this->kernel->stepper->acceleration_ticks_per_second ); // (step/min/acceleration_tick)
  96
  97     // Compute path unit vector
  98     double unit_vec[3];
  99     unit_vec[X_AXIS] = deltas[X_AXIS]*inverse_millimeters;
 100     unit_vec[Y_AXIS] = deltas[Y_AXIS]*inverse_millimeters;
 101     unit_vec[Z_AXIS] = deltas[Z_AXIS]*inverse_millimeters;
 102
 103     // Compute maximum allowable entry speed at junction by centripetal acceleration approximation.
 104     // Let a circle be tangent to both previous and current path line segments, where the junction
 105     // deviation is defined as the distance from the junction to the closest edge of the circle,
 106     // colinear with the circle center. The circular segment joining the two paths represents the
 107     // path of centripetal acceleration. Solve for max velocity based on max acceleration about the
 108     // radius of the circle, defined indirectly by junction deviation. This may be also viewed as
 109     // path width or max_jerk in the previous grbl version. This approach does not actually deviate
 110     // from path, but used as a robust way to compute cornering speeds, as it takes into account the
 111     // nonlinearities of both the junction angle and junction velocity.
 112     double vmax_junction = MINIMUM_PLANNER_SPEED; // Set default max junction speed
 113
 114     if (this->kernel->player->queue.size() > 1 && (this->previous_nominal_speed > 0.0)) {
 115       // Compute cosine of angle between previous and current path. (prev_unit_vec is negative)
 116       // NOTE: Max junction velocity is computed without sin() or acos() by trig half angle identity.
 117       double cos_theta = - this->previous_unit_vec[X_AXIS] * unit_vec[X_AXIS]
 118                          - this->previous_unit_vec[Y_AXIS] * unit_vec[Y_AXIS]
 119                          - this->previous_unit_vec[Z_AXIS] * unit_vec[Z_AXIS] ;
 120
 121       // Skip and use default max junction speed for 0 degree acute junction.
 122       if (cos_theta < 0.95) {
 123         vmax_junction = min(this->previous_nominal_speed,block->nominal_speed);
 124         // Skip and avoid divide by zero for straight junctions at 180 degrees. Limit to min() of nominal speeds.
 125         if (cos_theta > -0.95) {
 126           // Compute maximum junction velocity based on maximum acceleration and junction deviation
 127           double sin_theta_d2 = sqrt(0.5*(1.0-cos_theta)); // Trig half angle identity. Always positive.
 128           vmax_junction = min(vmax_junction,
 129             sqrt(this->acceleration*60*60 * this->junction_deviation * sin_theta_d2/(1.0-sin_theta_d2)) );
 130         }
 131       }
 132     }
 133     block->max_entry_speed = vmax_junction;
 134
 135     // Initialize block entry speed. Compute based on deceleration to user-defined MINIMUM_PLANNER_SPEED.
 136     double v_allowable = this->max_allowable_speed(-this->acceleration,0.0,block->millimeters); //TODO: Get from config
 137     block->entry_speed = min(vmax_junction, v_allowable);
 138
 139     // Initialize planner efficiency flags
 140     // Set flag if block will always reach maximum junction speed regardless of entry/exit speeds.
 141     // If a block can de/ac-celerate from nominal speed to zero within the length of the block, then
 142     // the current block and next block junction speeds are guaranteed to always be at their maximum
 143     // junction speeds in deceleration and acceleration, respectively. This is due to how the current
 144     // block nominal speed limits both the current and next maximum junction speeds. Hence, in both
 145     // the reverse and forward planners, the corresponding block junction speed will always be at the
 146     // the maximum junction speed and may always be ignored for any speed reduction checks.
 147     if (block->nominal_speed <= v_allowable) { block->nominal_length_flag = true; }
 148     else { block->nominal_length_flag = false; }
 149     block->recalculate_flag = true; // Always calculate trapezoid for new block
 150
 151     // Update previous path unit_vector and nominal speed
 152     memcpy(this->previous_unit_vec, unit_vec, sizeof(unit_vec)); // previous_unit_vec[] = unit_vec[]
 153     this->previous_nominal_speed = block->nominal_speed;
 154
 155     // Update current position
 156     memcpy(this->position, target, sizeof(int)*3);
 157
 158     // Math-heavy re-computing of the whole queue to take the new
 159     this->recalculate();
 160
 161     // The block can now be used
 162     block->ready();
 163
 164 }
 165
 166
 167 // Recalculates the motion plan according to the following algorithm:
 168 //
 169 // 1. Go over every block in reverse order and calculate a junction speed reduction (i.e. block_t.entry_factor)
 170 // so that:
 171 //   a. The junction jerk is within the set limit
 172 //   b. No speed reduction within one block requires faster deceleration than the one, true constant
 173 //      acceleration.
 174 // 2. Go over every block in chronological order and dial down junction speed reduction values if
 175 //   a. The speed increase within one block would require faster accelleration than the one, true
 176 //      constant acceleration.
 177 //
 178 // When these stages are complete all blocks have an entry_factor that will allow all speed changes to
 179 // be performed using only the one, true constant acceleration, and where no junction jerk is jerkier than
 180 // the set limit. Finally it will:
 181 //
 182 // 3. Recalculate trapezoids for all blocks.
 183 //
 184 void Planner::recalculate() {
 185    //this->kernel->serial->printf("recalculate last: %p, queue size: %d \r\n", this->kernel->player->queue.get_ref( this->kernel->player->queue.size()-1  ), this->kernel->player->queue.size() );
 186    this->reverse_pass();
 187    this->forward_pass();
 188    this->recalculate_trapezoids();
 189 }
 190
 191 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 192 // implements the reverse pass.
 193 void Planner::reverse_pass(){
 194     // For each block
 195     int block_index = this->kernel->player->queue.tail;
 196     Block* blocks[3] = {NULL,NULL,NULL};
 197
 198     while(block_index!=this->kernel->player->queue.head){
 199         block_index = this->kernel->player->queue.prev_block_index( block_index );
 200         blocks[2] = blocks[1];
 201         blocks[1] = blocks[0];
 202         blocks[0] = &this->kernel->player->queue.buffer[block_index];
 203         if( blocks[1] == NULL ){ continue; }
 204         blocks[1]->reverse_pass(blocks[2], blocks[0]);
 205     }
 206
 207
 208
 209
 210     //for( int index = this->kernel->player->queue.size()-1; index > 0; index-- ){  // Skip buffer tail/first block to prevent over-writing the initial entry speed.
 211     //    this->kernel->player->queue.get_ref(index)->reverse_pass((index==this->kernel->player->queue.size()-1?NULL:this->kernel->player->queue.get_ref(index+1)), (index==0? (this->has_deleted_block?&(this->last_deleted_block):NULL) :this->kernel->player->queue.get_ref(index-1)));
 212     //}
 213 }
 214
 215 // Planner::recalculate() needs to go over the current plan twice. Once in reverse and once forward. This
 216 // implements the forward pass.
 217 void Planner::forward_pass() {
 218     // For each block
 219     int block_index = this->kernel->player->queue.head;
 220     Block* blocks[3] = {NULL,NULL,NULL};
 221
 222     while(block_index!=this->kernel->player->queue.tail){
 223         blocks[0] = blocks[1];
 224         blocks[1] = blocks[2];
 225         blocks[2] = &this->kernel->player->queue.buffer[block_index];
 226         if( blocks[0] == NULL ){ continue; }
 227         blocks[1]->forward_pass(blocks[0],blocks[2]);
 228         block_index = this->kernel->player->queue.next_block_index( block_index );
 229     }
 230     blocks[2]->forward_pass(blocks[1],NULL);
 231
 232     //for( int index = 0; index <= this->kernel->player->queue.size()-1; index++ ){
 233     //    this->kernel->player->queue.get_ref(index)->forward_pass((index==0?NULL:this->kernel->player->queue.get_ref(index-1)),(index==this->kernel->player->queue.size()-1?NULL:this->kernel->player->queue.get_ref(index+1)));
 234     //}
 235 }
 236
 237 // Recalculates the trapezoid speed profiles for flagged blocks in the plan according to the
 238 // entry_speed for each junction and the entry_speed of the next junction. Must be called by
 239 // planner_recalculate() after updating the blocks. Any recalulate flagged junction will
 240 // compute the two adjacent trapezoids to the junction, since the junction speed corresponds
 241 // to exit speed and entry speed of one another.
 242 void Planner::recalculate_trapezoids() {
 243     int block_index = this->kernel->player->queue.head;
 244     Block* current;
 245     Block* next = NULL;
 246
 247     //this->kernel->serial->printf("tail:%d head:%d size:%d\r\n", this->kernel->player->queue.tail, this->kernel->player->queue.head, this->kernel->player->queue.size());
 248
 249     while(block_index != this->kernel->player->queue.tail){
 250         current = next;
 251         next = &this->kernel->player->queue.buffer[block_index];
 252         //this->kernel->serial->printf("index:%d current:%p next:%p \r\n", block_index, current, next );
 253         if( current ){
 254             // Recalculate if current block entry or exit junction speed has changed.
 255             if( current->recalculate_flag || next->recalculate_flag ){
 256                 current->calculate_trapezoid( current->entry_speed/current->nominal_speed, next->entry_speed/current->nominal_speed );
 257                 current->recalculate_flag = false;
 258             }
 259         }
 260         block_index = this->kernel->player->queue.next_block_index( block_index );
 261     }
 262
 263     // Last/newest block in buffer. Exit speed is set with MINIMUM_PLANNER_SPEED. Always recalculated.
 264     next->calculate_trapezoid( next->entry_speed/next->nominal_speed, MINIMUM_PLANNER_SPEED/next->nominal_speed); //TODO: Make configuration option
 265     next->recalculate_flag = false;
 266
 267 }
 268
 269 // Debug function
 270 void Planner::dump_queue(){
 271     for( int index = 0; index <= this->kernel->player->queue.size()-1; index++ ){
 272        if( index > 10 && index < this->kernel->player->queue.size()-10 ){ continue; }
 273        this->kernel->serial->printf("block %03d > ", index);
 274        this->kernel->player->queue.get_ref(index)->debug(this->kernel);
 275     }
 276 }
 277
 278 // Calculates the maximum allowable speed at this point when you must be able to reach target_velocity using the
 279 // acceleration within the allotted distance.
 280 double Planner::max_allowable_speed(double acceleration, double target_velocity, double distance) {
 281   return(
 282     sqrt(target_velocity*target_velocity-2L*acceleration*60*60*distance)  //Was acceleration*60*60*distance, in case this breaks, but here we prefer to use seconds instead of minutes
 283   );
 284 }
 285
 286